Gell coat repair
If water get up into the fibres you will have a serious job on your hands
It can only lead to greater problems.
Jack up stern of boat. Secure on both slides with some blocks of timber. Slowly ease the trailer out from under the boat. Add extra supports as required. YOu possibly will not have to completely remove the boat from the trailer.
A gel coat repair kit does not cost much. Dry the boat out well. Sand the area. Clean with acetone or thinners. Work the gel well into the area. Use flat blade knife to get it smooth as possible.
You probaly dont need to sand back the finished repair as it will go unnoticed. Consider a Keel gaurd.
Best of luck.
Take it easy ....but, take it all the way.